Elevator control system



Oct. 27, 1931.

G. W. LAUTRUF ET AL ELEVATOR CONTROL SYSTEM Filed Sept. 9I 1925 2 Sheets-Sheet l 351g, f hul/z @Hom/wijf OC- 27, 1931. G. w. LAUTRUPET AL 1,829,524

ELEVATOR CONTROL SYSTEM Filed Sept. 9l 1925 2 Sheets-Sheet 2 9 W QJ IUD o WM mw F/G. Z

en@ mm mm @www Patented Oct. 27, p

UNITED sTATEs raralvi orf-*Tea GEORGE W. LAUTRUP, OF `YONKERS NEW YORK, AND GEORGE N. CRABBE, OF ERESSKILL,

JERSEY, ASSIGNORSIO OTIS ELEVATOB COMPANY, OF JERSEY CITY, 4NEWT JERSEY, A. CORPORATION F NEW JERSEY ELEVATOR CONTROL SYSTEM Application filed September 9, 1925.V Serial No. 55,298.

The invention relates lto control systems and particularly to control systems for elevators. y o

Where power operated car gate and hatchway door mechanism is employed in elevator systems, itis desirable to have the mechanism operate in such manner as to effect the movem'ent of the gate and door 4into open positions by the time that the car has stopped at the floor. Such operation is advantageous particularly because of the amountp of time which is saved. In high speed elevator systems, thetime gained in making each stop is an' important factor and, when the, gain for a whole trip is considered, 41t may tem is raised considerably. It is further in the interest of 'operating efficiency, where mechanism is remployed to bring the c ar to a level with the desired landing in stopping, to cause the automatic gate and door'opening operation to occur duriiig the leveling period.

Thus with the gate and-door opening mechanism and leveling mechanism operating simultaneously, the. car gate andhatchway door are fully opened as the car is brought to a stopl level with the landing. In the event that the levelin operation is prolonged', as might bef caused y anoverrun, the gate and do/or are open during the latter portion of the leveling period. \In such an arrangement, however, the speed of thepcar might be accidentally increased during the'gate and door opening-operationor while the gate and,`

door are open with a passenger in the act, of

stepping into or out of the car.'

One feature of the invention is to prevent the occurrence'of excessive speeds during the 40,l p I. 'Other features and advantages will become leveling period.`

apparent 4from the following description, taken .in connection with the accompanying drawings wherein the invention is enibodied l in concrete form and in which: '.Figure 1 is a diagram of an elevator control'system; and

Fi ure 2 1s a schematic'representation of the ell evator car, showing the arran ement of the carswitch andpof mechanisms'uitablefor be seen` that the operating efiiciency of the whole sysefiecting the'leveling and car gate and hatch- 4Way dooropening operations.

Referring to Figure 1, no attempt is made to showthe coils and contacts 'f the variouselectromagnetic switches in their associated positions, a stijaight diagram being employed wherein the coils and contacts of the various1 switches are separated in such manner as to render the circuits involved relatively simple. Also lthe parts of other switches and apparatus areseparated inthe interest of simplifying the diagram. For af'clearer understanding of the invention, the stationary contacts of the switches are illustrated in cross section. It is to Abe understood that the system in which the invention is illustrated is chosen merely for convenience of description and that, although described in conjunctionV field winding 17 and itsauxiliary separately excited field winding 18. The elevator motor is designated as a7 wholeby the numeral 20, f its armature beingldesignated 21 and its field ,winding 22. An adjustable resistance 23 is arranged in shunt to the generator series field winding.. Discharge resistances 24 and 25 are provided for the generator separately ex#l scited field windings 17 ,and 18 respectively. Discharge Vresistance 26 is provided for the' elevator motor field winding 22. A resistanceJ 27 is provided; for controlling the strength of the generator field and therefore the voltage applled toy the'elevator motorv armature during car switch operation.. Another resistance 28 is provided for controlling the strength of thegenerator field duringaleveling operation. A resistance 29 controls the strength of the v eld winding. 16, its main separately excited elevator motor field during different conditions of operation. is the release coilefor the elevator motor electromagnetic brake. This coil is provided with discharge resistances 31, 32 and 33 for controlling the application gf the brake, under different conditions of operation. 34 and 35 are the up slow speed contacts and the down slow speedcon'- tacts respectively of the leveling switch, the

leveling switch up and down fast speed con- 'tact's being designated 36 and 37 respectively.

38 is the armature and 40 is the field windin of the motor 41'or moving the rollers of the leveling switch into position to clear the leveling cams. 42 is the armature and 43 is the field winding of the door control motor 44.

45 and 46 are the direct current supply mains. 47 is a double pole knife switch for connecting the system to the supply mains. In order to suit the type of diagram employed, the blades of this yswitch are shown separated. The ca-r switch is designated as a whole by -the numeral 48. 50 is the safety switch in the car. The series of door contacts are inv dicated byf a single set of contacts 51. The gate contacts are indicated as 52. The-va rious safety, iimit, stop and emergency `switches are omitted in order to simplify the K-Door control motor maintaining relay M-Maintaining relay N-Sequence relay l O-Accelerating relay P -Hard brake switch LB-Up leveling directionswitch LCV-Down leveling direction switch LH-#leveling brake and field switch Y LF-Fast speed leveling relay.A

Throughout the description which follows,

these letters, in addition to the usual ref-.

erence numerals, will be applied to the parts of the above enumerated switches. For eX- ample, contacts B 111 are contacts on the up main direction switch, while actuating coil A53 is the coil that operates the ypotential switch. The electromagnetic switches are shown in their deenergized positions. Reactances are similarly. designated by the character X.

Upon the' closing of the knife switch 47, the driving motor 11, elevator motor field winding 22 and potential switch actuating coil A 53l are energized, the circuit for coil A 53 being throughsafety switch 50. The

providing what may be termed a standing field. The circuit for the elevatorfmotor field winding may be traced from the lefthand blade of switch 47, line 55, by way of g Xline 56 through field winding 22, resistance section 54 and second accelerating switch contactsE 57, line 58, tothe right-hand blade of switch 47.- It is not desired to applyl full line voltage to the field winding 22 when the elevator motor is not in operation because of increased power consumption.

0n the other hand, itis not desired to have this field winding deenergized with the elevator motor at rest as a matter of safety and because of the time constant, involved in building up. y The potential switch, upon operation, causes theengagement of contacts A 60 and A 61, preparing the circuit for the generator separately excited field winding, the electromagneticbrake release coil andthe control circuits. The condition of the circuits so far described might be termed normal.

Referring briefiy to -Figure 2, the car switch 48 comprises a set of up contacts 62, y63, 64, and 66 and a set of down contacts 67, 68, 69, and 71. A contact segment 72 l:forl bridging the contacts. of each set is mounted on the segmental support 7 3 of insulating material. A cam 74 is formed on the support above the pivot point 75. The I cam is formed with a centrally disposed depression 7 6 into which the operating roller 77 of the gate and door switch 78 extends with the car switch in neutral or off posimeans of a control handle 81. It is'prenotferred to provide centering-springs shown) on the car switch to cause it' to be returned to off oposition-when released by the operator.

Referring'back to Figure 1, assume that several floors and that -the car is at rest at the first. floor with thel gate and door open. In the starting operation, the operator first gives the car switch a slight initial movement to effect the: closure of the gate and door switch 78. For convenience of description, this switch isarranged to complete a circuit for the door control motor switch actuating coil J 82. This circuit may be traced from the left-hand 4blade of switch 47, by Way of line 55 through contacts A 60, by way of line83 through coil J 82, resistt'ion. The switch 78is pivoted at'80 so that A the'system is designed for an installation of ance 84 and switch 78, line 85, switch 50, line 86,',line 58, to the right-hand blade of switch 47'. The door control motor switch,

upon operation, causes the engagement of contacts J 87, completing the circuit for the door control motor 44. This circuit may be traced/trom the left-hand blade of switch 47, by way of line 55 through contacts A 60,

by way of line 88 through contacts J 87,

door control motor field winding 43 and armature 42, by way offline 58 through conta'cts A 61, to the right-hand blade of switch 4 Referring again to Figure 2, the door control motor44' operates pneumatic gate and door operating mechanism, as for example through linkage 90 to move valve 91 for gate engine 92 to gate closed position and to withdraw the retiring'cam 93 from engagement with the roller provided von theend of 4o tion of motor 44 to move valve 91 and,

through cam 93 and lever 94, valve 95 into the door engine valve lever 94. The lever 94 is operated by a spring to move valve 95 for the door engine 96 to door closed position. The gatel and door engines operate through mechanism not shown to close the car gate 99 and hatchwaydoor 109. It is to be understood that a door 'is provided in the hatchway at each landing.

, Referring back to Figure 1, if the oper-y .positions to cause the reverse operations of the engines 92 and 96 to open the gate` and' door. Obviously other forms ofl power operated gate and door mechanisms, such as" electric in lieu of pneumatic, may be employedwithout departing from the spirit of the present invention.

Assuming that the gate and doors 'are closed, the gate contacts 52 and door contacts 51 are in engagement. AT he operatortmay now move the care switch to full operated position to start the car in the up direction. It is 55 tobe noted that the gate and door switch 78 ,remains in c-losed position so long as 'the car switch ismoved out of neutral fposition. Upon the engagement of contact segment 72 and Contact 64, circuits are simultaneously y C0 completed for the oppositely wound coils N 98 and N 1 0 of the sequence relay, actuating coils H 1 1 of the main brakevand field switch and B 1.02 of the up main direction switch being ini the circuit for coil AN 100.l The er1- C5 gagement of the contact segment and' contacts and 66 prepares circuits for the actuating coils of the accelerating switches:

The circuit for coil N 98 or the sequence relay may be traced from the left-hand blade of switch 47, by way of line 55-tlirough contacts A 60,by way of line 103 through coil N 98 and resistance 104, contacts 62 and 64 .ot' the car switch by way of line k105 through contacts C 106 of the down main direction` switch, line 85, to thefright-hand blade of switch 47 as above traced. The circuit for coil N may be traced from the lefthand `blade of switch 47, by way of line 55 through contacts A 60, by way of line 107 through door contactsl, gate contacts 52, sequence relay contacts N 108, and coils N 100, H 101 and B 102, contacts 63 and 64 0f the car switch, to the rightha-nd blade of switch 47 as above traced. The purpose of the sequence relay N is to insure the closure of the gate and doors before starting the car. Coils N 98 and N 100, being differentially wound, oppose each other, when energized simultaneously, to .prevent the operation ef therelay. If either coil is energized ahead of the. other, oriif either coil alone is energized, contacts N 108. separate, preventing the starting of the car. If either the gate contacts 52 or any of the door contacts 51 are separated at the time that carA switch segment 72 engages contacts64, coily N 98 alone is energized, resulting in the separation of contacts N `108.V The separation of contacts N 108 prevents the energization of coil Nl00, maintaining the sequence relay operated, and of coil B102, lpreventing the operation of the up mainV direct-ion switch to effect the starting of the car. The gate and door switch 78, therefore, is closed by the initial `movement of the car switch so that the gate and door contacts may be closed before the engagement of segment 72 and contact 64. However, if the car switch is moved into position where segment 72 engages contactv 64, before the closure of the door and gate contacts, the sequence relay operates t0 prevent the starting of the car. Thus it is im@ possible to start the car on the door or.` gate contacts. n 1 a,

Assuming that the sequence relay has opcrateri,I in orderot'o start the car the car switch isl returned to ai' position rwithv segment 72 disengaged from contact 64, deener'gizing coil N 98 to permit contacts IN 108 to reengage. A

If the gate and door are closed, the car switch maybe returned immediately to full on position. IOtherwise, closing of the gate and door must be effected before the car switch` is moved into full on position.

Y It is preferred to provide the mainidirection switches with a mechanical interlock to prevent their simultaneous operation. Such an interlock may be ofthe form of a walking beam pivotally mounted for engaging catchesl on the armatures of "these switches. Upon operation of the up main direction switch r in response to the emerga/ation of itsactuating1 coil B 102, contacts 110 separate and contacts B111, B 1,12 and B 113 engage.- ,separation of contacts B 110 breaks the clr-n icuit leading from the car switch down feed contact 69, contacts B 110 and the corres onding down direction switch contacts 106 serving as electrical interlocks as is well understood` in the art. The engagement of contacts B 113 prepares the circuit for the up main direction switch holding coil B 115 and the main brake and lield switch holding coil :H 116. The engagement o'contacts B 111 and B 112y completes a circuit for the generator main field windin 17. This circuit may be traced from the le t-hand blade of switch 47, by wayof line through contacts A60, resistance 27 and contacts B 111, by way of y line 117 through field winding 17, by way of line 58 through contacts B.112 and contacts A 61, to the right-hand blade of switch 47. The main brake and ield switch H operates simultaneously with the'main direction switch B. Switch H, upon operation,'causes the separation'of contactsH 119, H 122 and H 123 andthe engagementrof contacts H 124.

H 125, H126 andH 127. The separation of contacts .H 119 disconnects the generator main field winding from the generator armature. The purposeo this arrangement willw Abeez'zplained later. ,Contacts H 122 are 1n the circuit for the generator auxiliary field winding 18. The purpose of this arrangement also will be explained later. vThe separation of contacts H 123 disconnects resistance 33 from across the brake release coil 30. yResistance33 being ofslow ohmic-value, its disconnection,before contacts H 124 enga-ge prevents excess lpower consumption from 40 mains 45 and 46. The, engagement of contacts H 127 establishes a circuit for the door control motor maintaining relay actuating coil K 130. This circuit may be traced from the left-hand blade of switch 47, by way of 45 line 55 through contacts A 60, by wayof line 83 through coil J 82, by way of line 131 th rough up leveling direction switch contacts LB 132, down leveling direction switch contacts LC -133,'lcontacts H 127 and coil K 130,l line 85, to the right-hand blade of switch 47 Y. as previously traced. The. engagement ofv contacts H 125 further prepares the circuits for the actuating coils of the accelerating switches. The engagement of contacts H 126 short-circuits section 54 of the elevator motor eldresistance 29, permitting the motorvfield to build up to its full strength.' AThe engage-- ment of contacts H 124 completes theNcircuit oo for the brake release coil 30. This circuit 4maybe traced from 'the left-hand bladev of switch 47, by way of line 55 through contacts 1A 60, by way of line 134 thro ugh contacts 135 operated by the brake, brake releaser coil 30 35 and .contacts H 124, b5' way of line`58 through ject to the potential drop across resistance 84.

The system is arranged so that the voltage thus applied to coil K 130 is sufficient to etect the operation of the relay. Contacts K 136 engage, upon the operation of the relay, to

by-pass contacts H 1,27'. `The purpose of this arrangement will be seen from later description.

The brake release coil 30 being energized, the elevator motor eld beingY connected directlyA to the mainsr and 46 and current' being supplied from the generator armature l5 to the elevator motor armature 21, due to the energization of the generator main field winding, the elevator motor starts.

As the brake releases, the brake switch contacts 135 separate to insert cooling resistance 137 in series with the brake release coil. These brake' switch contacts are preferably arranged to be separated at the end of .the releasing operation. contacts 135 also breaks the short circuit around coil O 138, permitting the operation' of the yaccelerating relay O. This relay operates tocause the engagement of contacts 0 140, completing the Vcircuit for the first accelerating switch actuating coil D 141. The purpose Iof this arrangement is to utilize tlie time constant of the brake for timing t e celerating switch. Although the brake release coil is energized atv the same time that power is supplied to the motor, the brake shoes. do Vnot lift at once because of the inthroughcontacts A 60, by wayof line 1 07 Separation of acceleration of the motor', more specifil cally, for timing the operation of the first ace brake magnet l' be traced from the .4

cthrough the door" contacts 51, gate contacts 52and contacts N 108,by way of line 142 through contacts H 125, ,contacts O 140 and 4coil D 141, contacts 65 and 64 of the car switch, 'to the fright-hand blade of switchf 47 as previously traced. l

The operation of the first accelerating switch, in response to the energization of its actuating coil, causes the engagement of con! wtacts D 143, D 144, D 1,45 and D 146. The` engagement of contacts D 143 completes the circuity for the leveling switch motor 41? This circuit may be traced from the lefthandblade of switch 47 by way of line 55 through contactsAI 60, by way of line 147 through contacts D 143fie1d winding 40 and armature 38 of motor 41, by way of line 58'through contacts A 61,\to the right-hand blade 4vott switch 47 ...The leveling switch -Oiline 148 through coil H 116 and contacts D 144,"by way/of line 150 through coil 115 and contacts B 113, line 151,line 85, to the right-hand blade of switch 47 as previously traced. The purpose ofthe energization of 5 these holding coils will be seen from later description. The engagement of contacts D 146 completes the circuit for the second accelerating switch actuating coil E 152.

This circuitmay be traced from the left-v hand blade of switch 47,^by-way of line 55 through contacts A. 66, by wayofline 107 y through'door contacts'l, gate contacts 52 and contactsN 108, by waywof line 142 through contacts H 125, by wayof line 153 i throughy contacts D 146, reactance X 154 and coil E 152, car switch contacts 66' and 64, to the right-hand blade of switch 47 as previously traced. lThe engagement of contacts D 145 short-circuits section 155 of resistance 27, increasing the voltage applied to the generator main field winding. Thus the generatorE. M. F. is increased, 'increasing the speed of the motor. i

- The second accelerating-switch E does not operate immediately the circuit for its actuating coil is completed, its action. being'delayed by the eil'ect of reactance X 154. Upon operation, contacts E 156 and E 57 separate.

and contacts E 157 and E 158 engage. The separation of contacts E 156 removes the shunt circuit around a ortion of resistance 160. The separation oy contacts yE 156 before ,contacts E 158 engage prevents vexcess power consumption from mains and 46. The engagement of contacts E 158 completes t-he circuit'tor the firstpaccelerating switch holding coil D 161 and the maintaining relay actuating coil M l162. This circuit may be traced from the left-hand blade of switch 47, by way of line through contacts A, 60, by way ofline 151 through contacts E 158, reactance X 163, coil D I161 and-coil M 162, line .'85, to the right-hand blade of switch 47, as previously traced. The maintainin relay contacts M 164 are thus closed to Eby-pass contacts D 144. The (purpose of this arrangement Will be described later. The engagement of contacts E 157 short-circuits section. 165 of resistance 27 to increase thev voltage applied to the generator mainiield winding'. The E. M. F. of the generator, therefore', increases to its full value and the speed of the elevator motor increases. The separation of contacts E 57" removes the short '5 circuitvfor section 167 of resistance 29 inthe `tained through contacts parallel and coil K 130.

elevator motor field winding circuit, bringing the elevator motor up to full speed.

The starting ofthe car in the down direction is accomplished in a similar manner and will be only brieliy described. Theoperator iirst. moves the car switch into position 7 to cause the closure of' the gate and door and then into full on position where its contact segment 72 bridges contacts 67, 68, 69, 70 and 71. Thus the circuit is completed for the down main direction switch actuating coil C 168. This circuit may be traced from the left-hand blade of switch 47, throu lf coil H 101 as previously traced, by Way o line 170' through coil C 168, car switch contacts 68 and 69, by way of line 171 through contacts B 110, line 85, to thev right-hand blade of switch 47 as previously traced.. The circuit' for coil N 98 is by way of line 172. The circuit for coil D 141 is by way of line 173. The circuitlf'rcoil 'E 152 is by way of line 174; The 85 down main direction switch, upon operation, causes the separation of contacts C 106 and the engagement of contacts C 175, C 176 and C 177, these contacts corresponding with up o main direction switch contacts B 116, -B 111, B 112 and B 113 respectively. The holding coil of the downmain direction switch is designated C 178. Furtherthan this,`the o eration of'starting the car in the ,down if rection isthe same as described for starting it in the up direction. y

Assume that the car is running in the up direction and that the operator centers the car switch between the second and third floors in order to stop at the third floor landing. Thus the contact segment 72 moves off contacts 66, 65, 64 and 63and the circuits-:tor the second accelerating switch actuating coil E 152,- first accelerating switch actuatin coil'D 141, main brake and field switch actuating coil H 1,01, up main direction switch actuating coil B 102 and sequence relay coils N 98 and N 100 are broken. The second accelerating switch drops out immediately. The first accelerating switch, main vbrake and iield switch and up main direction switch are maintained operated, however, by ltlding' coil D`161H 116 and B 115 respectively. The deenergization of coils N 98 and N 100 l,

isin preparation for the next starting operation. It? is to be noted that switch 78 is opened by the centering of the car switch;l The circuit for coil J 82, however, is makin- The second accelerating switch, u on drop-'il ping out, causesthe separation o contacts E 157, and "E 158 and the' reengagement of contacts E 57 and E 156. The separation of 125 contacts E 157 reinserts section f165 of resistance 27 in ,series with the generator main lield winding to decrease the E.V M. F. of the generator. The engagement of contacts E 57 shortcircuits section 167 of resistance 29, in- 180 loo g los H127 and R136 in 12ok lay. The time element may be adjusted to the creasing' the strength of the elevatormotor In the stopping operation, upon the deeneld for the stopping operation. With the generator E. M. F. lowered and the strength of the elevator motor field increased, the

speed of the elevator motor is decreased. The l separation of contacts E 158 breaks the circuit for holding coil D 161 and coil M 162. The first accelerating switch D and maintaining relay M do not drop out immediately,

however, their action being delayed by the effect ofreactance X 163 in series with the coils and the discharge resistance 160 in parallel with the reactance and the coils. The engagement of contacts E 156 to'short-circuit a portion of resistance 160 is eiective .to prolong the time element of the switch and redesired value by changing the amount of the resistance portion short-circuited. Relay M is preferably adjusted to hold in at a smaller currentvalue than the acceleratin switch D. This may be readily accomplishe due to the fact that the relay is much smaller and there-L fore lighter in construction than the accelerating switch and requires less current to hold The first accelerating switch, upon dropping out, causes the separation of contacts D 143, D 144, D 145 and D 146. The separation of contacts D 144 is in preparation for the next starting operation, contacts M 164 re- ,maining in engagement to maintain holding coils H 116 and B 115 energized. The separation of contacts D 146 also is in preparation for the next starting operation, the circuit for coil E 152 having been broken by the movement of-the car switch as above de scribed. The separation of contacts D 145 removes the short circuit for section 155 of resistance 27, decreasing the strength of thev manner the operating rollers of the leveling switch are extended for engagement by the leveling cams. Referring brieiiy to Figure 2, the leveling switch motor is operatively connected to the leveling switch by means of an arm 180 on the motor shaft, a connecting link 181 and a lever '182. In the starting operation, the motor 41 being energized, arin 180 rotates, .acting through link 181 and lever 182 to move the levelingsw'itch as a whole about a pivot. n this manner the leveling switch operating rollersl 183..,and 184 are moved into position where they do not enga .fre the leveling cams 185 and I186 during f motion of the car, a stop being provided to determine the extent of. the movement. yIt is to be understood that leveling cams are provided for each floor. The leveling switch is pivoted on a bracket 187 'secured to the car frame.

the leveling switch up ergization. of the leveling switch motor, a sprin (not shown) moves the lever 18,2 and thereorethe leveling switch back into the rst described position with the rollers 183 and 184 extended for engagement by the leveling cams. Each pair of leveling switch contacts 34,35, 36 and 37 comprises a stationary contact and ay movable contact operated by the engagement of its corresponding roller and leveling cam. The. fast speed contacts 36 and 37 are arranged to separate before their corresponding slow speed contacts 34 and 35 in the leveling operation. Springs (not shown) are provided vfor causing the separationof the contacts of the pairs as the leveling eration is 'effected and stops are o provided fldr determining the extent of movement of the rollers as they ride off the leveling cams.

It will -be assumed that the car has not reached the landing and that the up leveling f .from the left-hand blade of switch 47 by way of linec` through contacts A GQ, line 191, leveling, switch contacts 34, by way of line' 192 through coil LB 188 and coil LH 190, line 85, to the right-hand blade of switch 47 as previously traced. yThe enga ement of fast spee contacts 36 completes the circult for fastspeed leveling relay actuating soil LF 193. This circuit may be traced from the left-hand blade of switch 47, by way of line 55 through contacts .A 60, line 191, leveling switch contacts 34, line 194, leveling switch contacts 36,.by way f line 85 through coil LF 193, fto the righthand blade of switch 47 as previously traced.

It is to be noted that, due to the fact that the circuit for coil LF 193.Y is through leveling switch slow speed contacts 34', the circuitfor coils LB 188 and'LH 190 must be made in order that the circuit for coil LF 193 may be completed.

p The up leveling direction switch LB,upon

operation, causes the separation of contacts LB' 132 andthe engagement of contacts LB i195, LB 196 and LB 197. YContacts LB 132 will be referred to later. The engagement of contactsLB 195,7and LB 196 prepares a circuit forthe generatorI auxiliary separately excited field winding 18. The engagement ofcontacts LB 197 completes the clrcuit for up series field relay actuating coil G 198 and up hard brake switch actuating coil P 200. This. circuit maybe traced from the left- .hand blade of switch 47, by way of line 55 l through contactsA 60, by way of line 201 through contacts LB 197, coil G 198, coil P- 200, and portion 202 of reactance X 203, line 204, by way of line 58 through contacts A 6,1', to the right-hand blade of switch 47.

The leveling brake and field switch, open i 207 "by-pass contacts H 124` in the circuit for gagement of contacts LF 214 by-passes conmaintaining relay coil K 130,'however, isi' Cal iactsLB 132, Lo las, H 127 and K 136, coil K 1,30 and switch 78 through resistance 84 in acircuit for coil J 82 of the door control motor switch. Sincethe engagement of contacts LF .214 generally occurs substantiallysimultaneously with the separation of contacts LB 132, the switch J does not drop out. Evenif switchJlshould drop out, the immediate reenergization .of coil J 82 upon the engagement -of contacts LF 214 would prevent the operation of the gate anddoor operating mechanism `.due to` the time required. for the mechanism to start in operation. The circuitI for the door control motor broken by the separation of contacts LB 132. y The separation of contacts LH 212 to break the circuit for resistance 160 as above set forth causes relay M to drop out and separate contacts lM 164. Asv aresult the circuit for holding coils B 115 and H 116 is broken, permitting the up main direction switch and main brake and field switch to dropy out.

Switch B, upon. dropping out,- causes the separation of contacts B 111, B 112 and B 113 and the engagement of contacts B110. The separation of contacts B 113 and the Vengagement of contacts B 110 is in preparation`r forl the next starting operation. The separation of contacts B 111 andB 112breaks the circuit'for the generator main field winding. However, the generator auxiliary field winding is simultaneously connected to thecmains by contacts H 122 of the main brake and field switch as set forth below. The switch H, upon dropping out, causes the separa-tion of contacts H124, H 125H 126 and H127 and the engagement of contacts H 119, H 122 and H 123. The separation of contacts H 125 and H 127.V is in preparation for the next starting operation. The separation of contacts H 124 and H 126 is without efiect, the circuit for the brake release coil 30 being maintained by contacts LH 207 and section 540i resistance 29 remaining short-` circuited by contacts LH 208. The engagement of contacts H 119 Vand H 123 also is without effect as the circuit for reconnecting the generator main field winding to the generator armature is maintained broken by v.contacts LH 206 and the shunt circuit for the brake release coil 30 comprising resistance 33 is maintained broken by contacts LH 205.v

The engagement of contacts H 122, however, completes the circuit for the generator auxiliary field winding. i This circuit may be traced from the left-hand blade of switch 47, by way of line 55 through contacts-A v60, by way of line 215 through contacts H 122 and contacts LF 213, ,by way of line 216 through contacts LB 195, through auxiliar field winding 18, back to line 215 throug contacts LB 196, by way of line 58 through contacts A 61, to the right-hand blade of switch 47. With'contacts LF 213 in engagement, short-circuiting resistance 28, an E. M. F. is generated which causes the elevator motor' to run at a suitable fast leveling speed. Discharge resistance 24 acts not only to smooth out the changes in generator E. M; F. due to the reinsertion of resistance their action beingl delayed by reactance X 203. Switch P, however, is adjusted to opcrate almost immediately and yupon operado notv operate irn-` mediately their actuating coils are energized,

tion, causes the separation of contacts P 221,

disconnecting resistance 32 from across the brake release.y coil 30. `Relay G, upon operatioi, causes the engagement of contacts G 222. 1

ing the circuit including resistance 23 in 13 shunt to the generator series field winding 16. The generator series field is so wound that, Without the parallelresistance 23, it would have too great an effect for proper operation of the car. The desired compounding is obtained by employing the low resistance shunt. 'Upon separation of contacts F225, the strength of the series field is increased for the leveling operation so as to aid in bringing the motor to a stop. The short delay in the action of the relay G, andV therefore switch F, upon`the initiation of the leveling operation, is desirable in order that the current in the generator armature-elevator motor armature-circuit may adjust itself to such a value that proper series field strength during the leveling operation may be obtained.

As thecar nears the third floor landing, roller 183 rides off the vertical surface onto the oblique surface of cam 18,5. This results in the separation of leveling switch up fast speed contacts 36, deenergizing fast speed leveling relay coil LF 193. Relay LF,'upon .dropping out, causes the separation of contacts LF 213 and LF 214." The separation of contacts LF 213 removes the short circuit for resistance 28. The generator E. M. F1 is thuslowered and the elevator motor runs at its slow leveling speed. The separation of contacts LF 214 breaks the circuit for the door control motor switch coil J 82. @Switch J, upon dropping out, causes the separation of contactsJ 87 to deenergize motor 44, thus effecting the automatic gate and door opening operation. The gate and door operating mechanism functions in the same'manner as described for/opening the gate and door in response to centerin the car switch. yIn this manner the automatlc gate and door opening operation is timed so that the gate and door open as the car stops at the landing. It is to be noted, however, that the automatic ate and door opening operation cannot take p ace until the leveling switch fast speed contacts out, causing the separation'of contacts LH 207 and LH 208 andthe reengagement of contacts LH 205, LH 206 and LH 212. The engagement of contacts LH 212 is' in preparatin for the next starting operation. The separation of contacts LH 207 breaks the circuit for the brake release' coil 30 and the accelerating relay coil 0138. Ducato the fact that the coil`30 discharges into resistance 31 of relatively high ohmic value, a hard application ofthe brake is "obtained The accelerating relay() drops out, separating contacts O 14.0*in preparation for the next standing starting operation. The separation of contacts LH 208 reinserts section 54 ofV resistance 29 in series with the elevator `motor field winding, reducing the current therein to a field value. of contacts LH 206 reconnects the generator main field winding'to the generator armature. The polarity of this connection is such that the generator sends current through the field winding in suchmanner as to o ose the flux which produces the generator M. F., thus tending to destroy the residual flux of the generator field.

Up leveling direction' switch LB, dropping out simultaneously with switch LH. causes the separation of contacts LB 195, LB 196 and LB 197 and the engagement of contacts LB 132. The engagement of contacts LB 132 is in preparation yfor the next starting operation. The separation of contacts LB 195A and LB 196 disconnects the generator auxiliary field winding from the mains, the main field winding being simultaneously connected to the generator armature by contacts LH 206 as set forth above.4 The separation of contacts LB 197 breaks thecircuit for coils G 198 and P 200. The relay G Adrops out i m mediately, but the dropping out of switch P is delayed slightly due to the effect of the re. actance X 203 and discharge resistance 226. It is to be noted that the discharge current for 'up co-il P 200 and the reactance passes through down coil P 227 in such direction as to cause coil'P 227 toassist coil P 200 in maintaining switch P in operated condition. Relay G, upon dropping out, causes the separation of contacts G 222 to deenergize coil F 223, switch F dropping out in turn to cause the engagement of contacts F 225. The e11- gagement ofcontacts F 225 reconnects re- The reengagement sistance 23 in parallel with the generator series field winding 16. Switch P, upon dropping out, causes the engagement of contacts P 221.

Thus the brake being applied and the generator separately excited field windings being disconnected from the mains, the caris brought to rest level with the third floor landing. The engagement of contacts LH 205, along with the delayed engagement of contacts P 221, places discharge resistances 32 and 33 in parallel with the brake release coil 30 to soften the application of the brake.

lVith the sequence ofroperations as above c described the car will be slowed-down and stopped level with the desired landingwith-l out sacrifice of smoothness should the car switch be centered with the car at a greater distance from the landing, the maintaining relay would hold in to effect, through its contacts M 164, the retention ofthe main direction switch and main brake and field switch in operated condition. Should relay M drop out before the leveling However, A

-byvway of line- 235 through contacts LC 233,

` Thus contacts lP 221 are in engagement and Lacasse switch contacts enga the subsequent engagement of the leve ing switch contacts as the leveling switch roller rides on to the cam would cause the operation of switches LB and LH and relay LF to bring thecar to a level with the lfloor. In the event that the car switch is centered late in the stopping opera.- tion, as for example when the leveling switch operating roller strikes the leveling cam upon the dropping out of the first acceleratrd ingy switch D, the immediate separation of contacts L11/212 forces the dropping out of the main direction switch and 'the main brake .and field switch to 'permit the limmediate change of connections for the field windings and thuslslow down the elevator motor more rapidly. In'this manner the tendency for the car to overrun the floor is reduced.

Should an overrun occur, however, the system is arranged so that the'operation of the switches is modified. Assuming in the alcovey contacts A 60, line 191, contacts 35, by way of line 230 ,through coil LC 228, by Way of lineI 192 through coil LH 190, line 85, to the right-hand blade of switch 47 as previously traced. Contacts LH 205, LH 206 and ,LH 212 are separated and contacts LH 207 and LH 208 are enga-ged so that the circuit for.

resistance 33 across the brake release coil is broken, the generator main field winding is disconnected from the generatorarmature, the brake release coil is energized and resistance section 54 'for the elevator motor field winding is short-circuited. Contacts LH 212 perform no Afunction during this operation.`

The .switch LC operates to cause the) separan tion of contacts LC 133 and the engagement voitconta'cts LC 231LC 232 and LC 233. The

separation of contactsLC 133 is without par- "ticular effect at this time. The engagement of contacts LC 231 and LC 232 connects the generator y* auxiliary@ eld `.winding to the mains through resistancl 28. Due to the res versal of the flow of current 'through the auxiliary field winding from that during the leveling operation upon the car approaching the iioor in the up direction, the car is caused `to start-in the down direction.

. The engagement of contacts LC 233 completedacircuit for the down series field relay actuating coil G 234 and thedown hard brake switch actuating coil P 227. This circuit may' be vtraced from the left-hand blade of switch 47, by way of line 55 throughl contacts A 60,

coil G 234, coilP 227 and portion 236 oir'u actance X 203, line 204, by way of' line 58 explained, switch P in operated condition.

Upon the engagement of contacts LC 233 on the overrun, the current supplied to coils G 234 and P 227 ymust reverse the fiuX in the re,- actance, thus taking a longer time to build up to a value suiiicient to cause the operation of relay G and switch P. Thus contacts F 225, `depending' for their operation upon the opera -tion of relay G, remain closed temporarily to insuie that fthe current in the 4generator ar` mature-motor armature circuit has fallen to a low value. series field winding may be flowing in"\ a direction such as to cause the lgeneration of an E. M. F. which is of proper polarity for operating the car in the down direction, im-

mediate increase in the strength of the series-` ield might result in an overrun in the down directions As the car returns to the floor, it is .stopped by the separation of the leveling switch slow `speed,contacts 35 in a manner similar to that described for approaching the fioor in thejup direction.

lf the overrun is great enough to cause the engagement ofthe leveling switch down fast Since theJ current inthe speed contacts 37 as well as the leveling switch down slow speed contacts 35, coil LF 193 is energized. As before, relay LF causes the engagement of contacts LF 213t`o shortcircuit resistance 28, increasing the generator voltage and causing the elevator motor to run at its fast leveling speed. Relay LFalso causes the engagement of contacts LF'214 to energize coil J 82 again in the e'nt that it has become deenergized. Upon such anover runq the automatlc gate and door opening operation ldoes not occur until contacts LF 214 separate, as previously described. Further than this, the operation on an overrun is as above described. f

Itis to be understood that the operator may control both the acceleration and retardation `oi the car by moving the car switch in steps.

Should the operator suddenly move the car switch from one position into the other, -i'or l example from up into down position, injury to the system vis prevented by contacts B which remain'separated until the up direction switch drops out. lt is to be noted that, when the car is suddenly reversed or stopped between floors or stopped by opening thev safety switch 50, the switch yP is not operated.

` a soft application of the brake is obtained.

rIhis arrangement for the control of the separately excited field windings prevents the elevator car moving at an excessive speed during the leveling period. The automatic opening of the gate and door during this period renders the feature of particular importance. In systems employing resistance in series with the elevator motor armature to control the speed of the motor during leveling, or where the voltage applied to the armature of the elevator" motor during leveling is controlled by means of resistance in series with the separately excited field winding of the generator which supplies power to the motor, there is always the possibility of all ora portion of such resistances becoming short-circuited or -grounded, causing the speed of the elevator motor to increase. If mechanism were employed, as in the present system, to effect the automatic opening 1 of the gate and door during the -leveling period, the sudden increasef in speed might occur while the gate and door were being opened, or after the gate and door were open when the leveling arrangement is'slow in bringing the car to a levelwith the landing. In the present system, the car cannot run at an excessive speed during the leveling period and, therefore. during the opening of the gate and door or while the gate and door 4are open. Due to the fact that the circuit for the main field winding 17 and resistance 27 is'broken by the main direction switch contacts, the accidental short-circuiting or grounding'of resistan ce 27 during the leveling operation can- 4not effect an increase in the speed of the elevator car. Also connections for`the leveling operation must be made in order to effect the automatic gate and door opening operation, since contacts on th'e leveling direction switches control the circuit for the gate motor maintaining relay actuating coil K 130. The auxiliary field winding, employed during leveling, is designed so as to cause the V-generation of an E. M. F. of a value which is suicent only to cause the` elevator motor to run at a fastleveling speed upon the'application of full line voltage to the winding. Thus an accidental short-circuit of resistance 28 during the gate and door opening operation or while the gate and door are open can do no more thancause the elevator motor to run at its fast leveling speed.

.As many changes could be made in the above arrangement and many `apparently widely ,different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above descri-ptiomor shown in the accompanying drawingslshall be interpreted as illustrative and not in a limiting sense.v

What is claimed is 1. In combination, an elevator car, a hoisting motor therefor, means for energizing said motor to operate the car at normal full speed, means for causing said motor to bring the car .to a level with a desired landing in stopping,

means for energizing said motor to operate the car at a speed not exceeding a speed considerably lower than normal full speed during the leveling operation a car gate, a hatchway door, mechanism for causing the opening of said gate and door, means responsive to the operation of the leveling means for causing the operation of said mechanism to .effect the opening of said gate and door, and means for preventing the energization of the motor to operate the car above said lower speed during the opening of said gate and door.

2. In combination, an elevator car, a hoisting motor therefor, means for starting said motor, a resistance for controlling the speed of ythe motor, means for short-circuiting said resistance to increase the speed of the motor to a certain speed, a hatchway door, mechanism for causing the opening of said door, and means for preventing an increase in the speed of the motor above a slower speed than said certain speed in the event of the short-circuiting of said resistance from anv cause during the opening of said door.4

3. In combination, an elevator car, a hoisting motor therefor, a source of current of a given voltage, a generator for supplying current to said motor, a field winding for said generator adapted, when said given voltage is applied thereto, to cause the generation of a voltage of a certain value for operating the motor at a fast speed, a second field wind ing for said generator` adapted, vwhen said given voltage is applied'thereto, to cause the generation of a voltage of a lower value than i said certain value for operating the motor at a. slowbspeed, means for causing the 'application of said given voltage to either of said windings, andomeans for preventing the ap-V plication of voltage to either 911e of said windings while voltage is applied to the other.

4. In combination, an elevator car, a hoist-1 ing motor therefoxgla generator for supplying current to said motor, said generator having' a main eld winding and an auxiliary field winding, a source of current, means for connecting said main field Winding to said source -to cause the motor to run at a. certain speed, means for causingthemotor to level the car with a desired landing in stopping ata slower speed than said certain speed, said second named means comprisfing means for connecting said auxiliary` winding directly' to" said source, and means yfor preventing the connecting of the main field winding and the auxiliary field Winding to said source at the Sametime.

5. In combination, an elevator car, a hoisting motor therefor, a generator for supplying current to said motor, said generator having two field windings, a source of current, means for causing the motor to run at a certain speed, said means comprising means for-connecting one of said windings to said source, a hatchway door, mechanism for causing the opening of the door, and means for preventing the motor running above a slower speed than said certain speed during the opening of said door or while the door is open, said last named means comprising means for disconnecting said one winding and for connecting the other winding to said source.

6. In combination, an elevator car, a hoisting motor therefor, a generator for supplying current `to said motor, said generator initiating the operation of said mechanism during the operation of said second named means.

7. In combination, an elevator car, a hoisting motor therefor, a generator for supplying current to ysaid motor, said generator having a main field winding and an auxiliary field winding, a source of current, a resistance, means for connecting the main field winding to the source in circuit with the resistance to cause the starting of the.l

motor, means for short-circuiting said resistance to increase the speed of the motor, `a car gate, a hatchway door, gate and door opening mechanism, and means yfor permit'- ting the motor to run at a slower speed than said certain speed, but preventing an increase in speed in the event of the shortcircuiting of said resistance from any cause during the operation of said mechanism and while said gate and door are open, said last named means comprising means for disconnecting the main field winding and resistance `from said source and connecting the auxiliary winding thereto.

8. In combination; an elevator car; a hoisting motor therefor; a generator for supplying current to said motor, said generator having a main field winding -and an auxiliary field winding; a source of current; a resistance; means 'for starting said motor, said means comprising means for connecting said main field winding to said source in circuit with said resistance and for thereafter shortcircuiting the resistance to bring the motor up to full speed; means for bringing the car to a level with a desired landing in stopping, said second named means comprising means for disconnecting said main field lwinding and for connecting said auxiliary field winding to said source to cause the motor to run at a fast leveling speed, a second resistance, and means for causin the insertion of said second resistance in circuit with said auxil-v iary winding to cause the motor to run at a slow leveling speed; a car gate; a hatchway door; and means responsive to the operation of said means for causing the insertion of said second resistance in circuit with said auxiliary winding for causing the opening of said ate and door.

9. n combinatioman elevator car, a hoisting motor therefor, a generator for supplying current to said motor, said generator having two field windings, a source of current, means for energizing one of said field windings from said source to cause the generation of a voltage of a certain value for o erating the motor at a certain speed, means or energizing the other winding from said source l to cause the generation'of a. voltage of a lower value than said certain value for operating, the motor at a lower speed than said certain speed, and means for preventing the energization of both of said windings at the same time.

, 10. In an electric elevator, the combination with an electric hoisting motor, and a car driven thereby, of a motor generator connected to the motor, the generator being provided with a high-speed field and a low-speed field, means forautomatically cutting in resistance in the high-speed field to automatically slow the car, means for automatically transferring the control of the car from the high-speed field to the low-speed field beforel stopping the car, and means operative' through the low-speed field to accurately level the car with a landing.

In testimony whereof, we have signed our names to this s ecification.

EORGE W. LAUTRUP. GEORGE N. CRABBE. 

